1. Field of the Invention
The present invention relates generally to a system and method for communication between a mobile station and a wireline network, particularly, to an improved system and method for the transmission of data packets between a wireless subscriber and a wireline network, and, more particularly, to an improved system and method for data transmission between disparate telecommunication services utilizing a common protocol.
2. Background and Objects of the Present Invention
The evolution of wireless communication over the past century, since Guglielmo Marconi's 1897 demonstration of radio's ability to provide continuous contact with ships sailing the English Channel, has been remarkable. Since Marconi's discovery, new wireline and wireless communication methods, services and standards have been adopted by people throughout the world. This evolution has been accelerating, particularly over the last ten years, during which the mobile radio communications industry has grown by orders of magnitude, fueled by numerous technological advances that have made portable radio equipment smaller, cheaper and more reliable. The exponential growth of mobile telephony will continue to rise in the coming decades as well, as this wireless network interacts with and eventually overtakes the existing wireline networks.
Conventional wireline systems, commonly referred to as the Public Switched Telephone Network (PSTN), as well as early wireless systems, such as the Advanced Mobile Phone Services (AMPS) used in the United States, provide a fixed communications path between the message source and the destination. This fixed circuit switching technique establishes a dedicated connection or allocation of system resources, i.e., a radio channel between a base station and mobile terminal, and a dedicated phone line between the associated mobile switching center and the PSTN, for the entire duration of the call. Although such dedicated connections are useful in maintaining voice communications, which generally involve the transfer of a continuous stream of voice data which lasts for a relatively long period of time, circuit switching is not very efficient for data communications, particularly wireless data communications, because the short, bursty data transmissions are often followed by lengthy periods of inactivity, resulting in a waste of resources.
With the proliferation of computers, facsimiles, electronic mail (e-mail), short messaging and other services, the transmission of data, particularly in packet form, is becoming more prevalent. In an effort to provide a more efficient network framework for wireline data transmission, the Integrated Services Digital Network (ISDN) was developed to complement the PSTN and provide improved data services between network nodes and end-users.
In the wireless technology area, the United States cellular industry in 1993 developed the Cellular Digital Packet Data (CDPD) standard which co-exists with conventional voice-only cellular systems such as AMPS. CDPD overlays the existing cellular infrastructure and utilizes the unused air time on vacant cellular voice channels to transmit data packets therein.
Although CDPD and similar systems, such as the General Packet Radio System (GPRS) for the European Global System for Mobile Communication (GSM), attempt to optimize the scarce radio and access network transport resources, it should be understood that these systems operate independently and include their own functions and protocols for the set-up and release of packet data connections, functions and protocols absent in the underlying system.
In view of the above discussion, it is apparent that there are a number of disparate data communications systems and protocols, currently in use and proposed for use, each managing services with different characteristics, e.g., voice, circuit switched data, packet data, etc. What is needed is a uniform mechanism for handling the various types of information, particularly, in the wireless arena.
One such mechanism in the wireline area that has substantially increased the bandwidth of ISDN communications is Broadband ISDN (B-ISDN), which is based on Asynchronous Transfer Mode (ATM) technology that allows packet switching rates of up to several Gbps. ATM is a packet switching and multiplexing technique specifically designed to handle both voice users and packet data users in a single physical channel. ATM supports bidirectional transfer of data packets of fixed length between two end points, while preserving the order of transmission. More importantly, through use of B-ISDN call controls and ATM technology, disparate services having different characteristics are handled in a uniform way. As an example of the bearer service characteristics of B-ISDN, every bearer is characterized by a set of parameters such as bandwidth, delay, delay variation, cell loss ratio, etc., all of which may be found in ITU-T Recommendation Q.2931.
It is, accordingly, an object of the present invention to provide an improved system and method for the uniform handling of disparate services having different characteristics in a wireless environment.